In arthroscopic surgery, a torn or ruptured ligament or tendon may be treated by attaching an end of a tendon or ligament graft to bone. The graft end may be secured to the bone by any of a variety of devices and techniques. One common procedure, for example, involves the replacement of the anterior cruciate ligament (ACL) of the knee. In such operations, a tunnel is typically prepared through the patient's tibia, across the interarticular joint and into the femur. A hamstring tendon graft or a bone-tendon-bone graft may be attached to an implantable graft fixation device or screw or the like which is frequently planted in the femoral tunnel to help anchor one end of the graft therein. The other end of the graft is secured in the bone tunnel in the tibia or otherwise secured to the tibia.
Known configurations of such implantable devices incorporate various methods of mounting the graft. Typically, the method of anchoring a graft to bone is dependent upon whether the graft is made of soft tissue, such as a hamstring tendon graft, or whether a bone-tendon-bone type graft is used. By way of example, one method for ACL reconstruction uses a bone-tendon-bone graft and an interference screw, which may be inserted into a bone tunnel parallel to the bone block of the bone-tendon-bone graft. According to this method, holes are typically drilled in the bone block for passing sutures, which serve to pull the graft through the tunnel and into place. The bone block is then anchored in the bone tunnel by inserting an interference screw in the tunnel adjacent the bone block. The compressive action of the screw threads against the bone block and tunnel walls is intended to anchor the bone block of the graft in place.
Alternatively, ACL reconstruction may be accomplished with a hamstring tendon graft. This type of graft has also been secured in a bone tunnel with an interference screw. In this situation, an interference screw may be wedged between the soft-tissue graft and the bone tunnel to anchor the end of the graft in the tunnel. Soft tissue graft fixation may alternatively be accomplished by placing a pin transversely through the femoral tunnel and through the loop of a hamstring graft which is doubled over the transverse pin. Fixation using the cross pin involves preparation of a bone tunnel for placement of the graft and an additional, transverse bone tunnel for the transversely oriented pin.
Known devices and methods for installing and anchoring soft tissue and bone-tendon-bone grafts suffer from inadequacies which can result in damage to the graft, excess trauma to the patient receiving the graft, and/or an increase in post-operative recovery time. In particular, many known devices and graft fixation methods do not allow for satisfactory tensioning of the graft. For example, when an interference screw is used to anchor one end of the graft in a bone tunnel, the screw typically must be removed in order to adjust graft tension. Such removal can cause the graft to tear. Further, the use of an interference screw may prevent a portion of a graft and/or a bone block, or bone anchor, from contacting with the bone tunnel, which may slow the healing process.